Hey, do they have to be Spec-Fic YA books? If not, then I have fond memories of Robert Westall's The Machine Gunners. Rather than try to write one of my clumsy synopses, I'll just link to the Wikipedia page.

I remember this best for the BBC TV adaptation in the '80s, (That scene where Rudy turns himself in and tries to mediate between the kids and the Home Guard, and Chaz pulls the trigger... Still makes me shiver.) but I also read the book later, and a few years ago ny nephew read it for his school English class, so it is evidently still around.

And if books here do have to be speculative, I also remember reading a short ghost story by the same author and featuring the same protagonist called The Haunting of Chaz Mgill